The present invention is related to compounds that are S1P1/Edg1 receptor agonists and thus have immunosuppressive, anti-inflammatory and hemostatic activities by modulating leukocyte trafficking, sequestering lymphocytes in secondary lymphoid tissues, and enhancing vascular integrity. The invention is also directed to pharmaceutical compositions containing such compounds and methods of treatment or prevention.
Immunosuppressive and antiinflammatory agents have been shown to be useful in a wide variety of autoimmune and chronic inflammatory diseases, including systemic lupus erythematosis, chronic rheumatoid arthritis, type I diabetes mellitus, inflammatory bowel disease, biliary cirrhosis, uveitis, multiple sclerosis and other disorders such as Crohn's disease, ulcerative colitis, bullous pemphigoid, sarcoidosis, psoriasis, autoimmune myositis, Wegener's granulomatosis, ichthyosis, Graves opthalmopathy, atopic dermatitis and asthma, chronic pulmonary disease, acute lung injury, acute respiratory distress syndrome, and sepsis. They have also proved useful as part of chemotherapeutic regimens for the treatment of cancers, lymphomas and leukemias.
Although the underlying pathogenesis of each of these conditions may be quite different, they have in common the activation of the immune system and the appearance of a variety of autoantibodies, self-reactive lymphocytes and/or activation of cells involved in innate immunity. Such self-reactivity may be due, in part, to a loss of the homeostatic controls under which the normal immune system operates. Similarly, following a bone-marrow or an organ transplantation, the host lymphocytes recognize the foreign tissue antigens and begin to produce both cellular and humoral responses including antibodies, cytokines and cytotoxic lymphocytes which lead to graft rejection.
One end result of an autoimmune or a rejection process is increased vascular permeability and tissue destruction caused by inflammatory cells and the mediators they release. Anti-inflammatory agents such as NSAIDs act principally by blocking the effect or secretion of these mediators but do nothing to modify the immunologic basis of the disease. On the other hand, cytotoxic agents, such as cyclophosphamide, act in such a nonspecific fashion that both the normal and autoimmune responses are shut off. Indeed, patients treated with such nonspecific immunosuppressive agents are as likely to succumb to infection as they are to their autoimmune disease.
Cyclosporin A is a drug used to prevent rejection of transplanted organs. FK-506 is another drug approved for the prevention of transplant organ rejection, and in particular, liver transplantation. Cyclosporin A and FK-506 act by inhibiting the body's immune system from mobilizing its vast arsenal of natural protecting agents to reject the transplant's foreign protein. Cyclosporin A was approved for the treatment of severe psoriasis and has been approved by European regulatory agencies for the treatment of atopic dermatitis.
Though they are effective in delaying or suppressing transplant rejection, Cyclosporin A and FK-506 are known to cause several undesirable side effects including nephrotoxicity, neurotoxicity, and gastrointestinal discomfort. Therefore, an immunosuppressant without these side effects still remains to be developed and would be highly desirable.
The immunosuppressive compound FTY720 is a lymphocyte sequestration agent currently in clinical trials. FTY720 is metabolized in mammals to a compound that is a potent agonist of sphingosine 1-phosphate receptors. Agonism of sphingosine 1-phosphate receptors modulates leukocyte trafficking, induces the sequestration of lymphocytes (T-cells and B-cells) in lymph nodes and Peyer's patches without lymphodepletion, and disrupts splenic architecture, thereby interfering with T cell dependent antibody responses. S1P receptor agonists also have anti-inflammatory properties by enhancing endothelial integrity and inhibiting vascular damage consequent to the activation of the immune system. Such immunosuppression and antiinflammation is desirable to prevent rejection after organ transplantation, in the treatment of autoimmune disorders, and in the treatment of conditions that have an underlying defect in vascular integrity, such as acute lung injury, acute respiratory distress syndrome, and sepsis, —see Groeneveld, A. B. J. 2003. Vascular Pharm. 39:247-256.
Sphingosine 1-phosphate is a bioactive sphingolipid metabolite that is secreted by hematopoietic cells and stored and released from activated platelets. Yatomi, Y., T. Ohmori, G. Rile, F. Kazama, H. Okamoto, T. Sano, K. Satoh, S. Kume, G. Tigyi, Y. Igarashi, and Y. Ozaki. 2000. Blood. 96:3431-8. It acts as an agonist on a family of G protein-coupled receptors to regulate cell proliferation, differentiation, survival, and motility. Fukushima, N., I. Ishii, J. J. A. Contos, J. A. Weiner, and J. Chun. 2001. Lysophospholipid receptors. Annu. Rev. Pharmacol. Toxicol. 41:507-34; Hla, T., M.-J. Lee, N. Ancellin, J. H. Paik, and M. J. Kluk. 2001. Lysophospholipids—Receptor revelations. Science. 294:1875-1878; Spiegel, S., and S. Milstien. 2000. Functions of a new family of sphingosine-1-phosphate receptors. Biochim. Biophys. Acta. 1484:107-16; Pyne, S., and N. Pyne. 2000. Sphingosine 1-phosphate signalling via the endothelial differentiation gene family of G-protein coupled receptors. Pharm. & Therapeutics. 88:115-131. Five sphingosine 1-phosphate receptors have been identified (S1P1, S1P2, S1P3, S1P4, and S1P5, also known as endothelial differentiation genes Edg1, Edg5, Edg3, Edg6, Edg8), that have widespread cellular and tissue distribution and are well conserved in human and rodent species (see Table). Binding to S1P receptors elicits signal transduction through Gq-, Gi/o, G12-, G13-, and Rho-dependent pathways. Ligand-induced activation of S1P1 and S1P3 has been shown to promote angiogenesis, chemotaxis, and adherens junction assembly through Rac- and Rho-, see Lee, M.-J., S. Thangada, K. P. Claffey, N. Ancellin, C. H. Liu, M. Kluk, M. Volpi, R. I. Sha'afi, and T. Hla. 1999. Cell. 99:301-12. S1P enhances endothelial barrier integrity by assembling cortical actin cytoskeletal structures and strengthening cell:cell junctions and cell:extracellular matrix interactions through S1P receptors, primarily S1P1-, see Garcia, J. G. N, F. Liu, A. D. Verin, A. Birukova, M. A. Dechert, W. T. Gerthoffer, J. R. Bamburg, D. English, 2001. J. Clin. Invest. 108:689-701, and S1P receptor agonists, including FTY720, can inhibit vascular permeability induced by VEGF in mice, see Sanchez, T., T. Estrada-Hernandez, J.-H. Paik, M.-T. Wu, K. Venkataraman, V. Brinkmann, K. Claffey, and T. Hla. 2003. J. Biol. Chem. 278:47281-47290.
Administration of sphingosine 1-phosphate to animals induces systemic sequestration of peripheral blood lymphocytes into secondary lymphoid organs, thus resulting in therapeutically useful immunosuppression, see Mandala, S., R. Hajdu, J. Bergstrom, E. Quackenbush, J. Xie, J. Milligan, R. Thornton, G.-J. Shei, D. Card, C. Keohane, M. Rosenbach, J. Hale, C. L. Lynch, K. Rupprecht, W. Parsons, H. Rosen. 2002. Science. 296:346-349. However, sphingosine 1-phosphate also has cardiovascular and bronchoconstrictor effects that limit its utility as a therapeutic agent. Intravenous administration of sphingosine 1-phosphate decreases the heart rate, ventricular contraction and blood pressure in rats, see Sugiyama, A., N. N. Aye, Y. Yatomi, Y. Ozaki, and K. Hashimoto. 2000. Jpn. J. Pharmacol. 82:338-342. In human airway smooth muscle cells, sphingosine 1-phosphate modulates contraction, cell growth and cytokine production that promote bronchoconstriction, airway inflammation and remodeling in asthma, see Ammit, A. J., A. T. Hastie, L. C. Edsall, R. K. Hoffman, Y. Amrani, V. P. Krymskaya, S. A. Kane, S. P. Peters, R. B. Penn, S. Spiegel, R. A. Panettieri. Jr. 2001, FASEB J. 15:1212-1214. The undesirable effects of sphingosine 1-phosphate are associated with its non-selective, potent agonist activity on all S1P receptors.
The present invention encompasses compounds which are agonists of the S1P1/Edg1 receptor having selectivity over the S1P3/Edg3 receptor. An S1P1/Edg1 receptor selective agonist has advantages over current therapies and extends the therapeutic window of lymphocyte sequestration and vascular integrity agents, allowing better tolerability with higher dosing and thus improving efficacy as monotherapy.
While the main use for immunosuppressants and antiinflammatory agents is in treating bone marrow, organ and transplant rejection, other uses for such compounds include the treatment of arthritis, in particular, rheumatoid arthritis, insulin and non-insulin dependent diabetes, multiple sclerosis, psoriasis, inflammatory bowel disease, Crohn's disease, lupus erythematosis, asthma, allergies, chronic pulmonary disease, acute lung injury, acute respiratory disease syndrome, sepsis and the like.
Thus, the present invention is focused on providing immunosuppressant and vascular integrity compounds that are safer and more effective than prior compounds. These and other objects will be apparent to those of ordinary skill in the art from the description contained herein.
Summary of S1P Receptors
Coupled GNameSynonymsproteinsmRNA expressionSIP1Edg1, LPB1Gi/oWidely distributed,endothelial cellsS1P2Edg5, LPB2,Gi/o, Gq,Widely distributed, vascularAGR16, H218G12/13smooth muscle cellsSIP3Edg3, LPB3Gi/o, Gq,Widely distributed,G12/13endothelial cellsS1P4Edg6, LPC1Gi/oLymphoid tissues,lymphocytic cell linesS1P5Edg8, LPB4, NRG1Gi/oBrain, spleen